The present invention relates to tobacco harvesters and more particularly to a method and apparatus for automatically defoliating a selected vertical portion of an individual tobacco plant.
Tobacco of the bright leaf or flu-cured type grows to a height of 6 feet or more in the form of a single vertical stalk having numerous leaves extending upwardly and outwardly. The leaves grow from the stalk at an angle of approximately 50.degree. from the horizontal and droop somewhat under their own weight. The tobacco leaves are spaced spirally on the stalk throughout 360.degree. and ripen progressively from the bottom to the top of the stalk over period of 6 to 8 weeks. The leaves are desirably harvested only at a particular stage in the ripening process. This desideratum is achieved only by a number of separate harvesting operations.
In the hand "cropping" or harvesting of tobacco, the uppermost leaf adjudged by its color to be ripe for harvesting is grasped with the hand. That lead, and subsequently, the leaves lower down the stalk are snapped therefrom by a sharp, downward movement of the hand. The work is extremely hot, dusty, and gummy from the bleeding of the leaves.
While the steps of transplanting, cultivating, topping, and suckering tobacco plants have been mechanized to reduce the labor requirements, attempts to mechanize the harvesting or defoliating process have been generally unsatisfactory. Farm labor is today difficult to obtain. Thus the cost of the labor necessary to pass through a field four, six, or more different times, removing only ripened leaves from the stalk, constitutes a disproportionately large part of the total cost of raising tobacco.
It is accordingly an object of the present invention to provide a novel method and apparatus for the mechanized defoliation of a selected vertical section of a tobacco plant.
Many attempts to mechanize the harvesting of tobacco have been made. Among these is the harvester disclosed in the Pickett et al U.S. Pat. No. 3,507,103. In this case the defoliating apparatus of a self-propelled harvester is suspended by flexible cables from a wheeled carrier to provide for movement of the defoliating apparatus. Such suspension systems are advantageous in that the defoliating apparatus will assume a vertical orientation under the influence of gravity thereby increasing compatibility with the vertical stalks of the tobacco plants irrespective of terrain contour.
Because the defoliating apparatus must pass on opposite lateral sides of the tobacco plant to accomplish the cropping of leaves therefrom, the defoliating apparatus is longitudinally divided into two units. Suspension systems such as that disclosed in the Pickett et al patent effect independent suspension of these two lateral units. Misalignment of the two units relative to one or more plants is thus possible. The pressure of a stalk laterally against one of these units may effect lateral movement thereof while the other unit retains its vertical orientation due to gravity. Such relative movement tends to create an undesirably large space between the two units.
Therefore, still another object of the present invention is to provide a mechanical tobacco harvester in which the defoliating apparatus is laterally movable as a unit in response to the lateral pressure of tobacco plants passing therethrough.
Weather is also a continuing problem in that the tobacco plants are occassionally blown or beaten into positions far from the normal vertical position by wind, hail or the like. The mechanical defoliation of plants in this circumstance is generally impossible.
It is still a further object of the present invention to provide a mechanical defoliator with the capacity to straighten up wind blown plants in the defoliation thereof. To this end the pivotal suspension and stalk gripping character of the defoliating apparatus is quite useful.
It is customary in the mechanized planting of tobacco to plant four rows at a time spaced sufficiently to permit the movement of a tractor between adjacent four row plantings. Due to the lateral proximity of the four rows and the size of the individual tobacco plants, it is desirable that the wheeled vehicle traffic between the four rows be minimized.
Thus, yet another object of the present invention is to provide a novel tobacco harvester which may be drawn by a tractor passing along the area between adjacent four row plantings and in which only a single small, non-driven wheel need pass between any of the four rows of tobacco plants.
Still a further object of the present invention is to provide a mechanical tobacco harvester in which a defoliating unit is selectively positionable to harvest the outside or second row of the four rows in a planting, without the necessity for altering the wheel between the rows of the four row planting.
These and many other objects and advantages of the present invention will be readily apparent from the claims and from the following detailed description when read in conjunction with the appended drawings.